GPD XD, It's portable, pocketable even as it has a clamshell design like the NDS, its the same size and form factor as the New 3DS XL, includes dual analog sticks, 4 shoulder buttons and even L3 and R3 buttons. A lot of happy customers, myself included and can run all those emulators pretty well with a few problems Dreamcast-side in my opinion.
You can see a lot of chat about this console, its pros and cons and other GPD devices here - http://boards.dingoonity.org/gpd-devices/
Of course being a Chinese console, it has its problems too, some people have issues with the setting of the buttons, some say its too mushy but I like it, so its all down to personal opinion there. Some actual issues such as the CPU wuring while the device is on was also present but I believe a firmware update fixed this.
They are good with community support to, firmware updates come out pretty often.